In the field of hydraulics, it is desirable to determine the position of a spool within a directional valve. For example, information pertaining to the position of the spool may be used for closed-loop control of the directional valve providing for improved system performance.
The most common method of determining spool position is the use of such sensors as potentiometers or linear voltage differential transformers (LVDTs). While these sensors provide the desired information, such sensors have serious deficiencies owing in part to difficulties in mounting the units and the harsh environmental conditions to which they are exposed.
Sensors used on hydraulic systems in the heavy equipment industry are particularly subject to damage from the severe work environment. Hydraulic directional valves are typically located in relatively unprotected areas and subjected to, for example, high g-forces, wide temperature variations, dust, water, debris, etc., which can result in both electrical and mechanical failure of the sensor.
The present invention is directed to overcoming one or more of the problems as set forth above.